C(NH2)3]2TaF7 and [C(NH2)3]3TaF8: Guanidinium fluoride-tantalates with isolated anionic polyhedra

Abstract

Two guanidinium fluoride tantalates have been prepared by the reacting of guanidinium carbonate with TaF5 in aqueous HF solutions. The reaction with [C(NH2)3]2CO3:TaF5 2.5:1 M ratio in 33% hydrofluoric acid aqueous solution resulted in the formation of [C(NH2)3]2TaF7 compound. Similar procedure with 3:1 M ratio performed in 5% HF aqueous solution resulted in the formation of a [C(NH2)3]3TaF8 salt. The X-ray single crystal structures of the compounds were determined to contain discrete TaF72– and TaF83- anions of capped trigonal prismatic and square antiprismatic shapes, respectively. Both compounds were also characterized by Raman spectroscopy.